a) Field of the Invention
The present invention relates to a tilt switch, and more particularly to a tilt switch which is installed on all kinds of machines including an electronic machine, a control device, or a measurement machine, for detecting their tilt or vibration.
b) Description of the Prior Art
A ball member vibration switch, as disclosed by the Taiwanese Utility Model Patent No. 468865, includes an insulating housing, an interior of which is provided with an electrically conductive metal ball member and a plurality of electrically conductive terminals. By tilt of the insulating housing, the ball member will move between positions where the ball member is and is not in contact with the terminals, to perform an ON/OFF operation of the switch, so as to detect the tilt or vibration of a machine which is installed with this switch.
Referring to FIGS. 9 to 11, this switch is provided with an insulating housing 10, an opening part of which has a larger diameter, and a bottom part of which is formed with an accommodating space 101 in a shape of a funnel. An electrically conductive ball member 102 is movable and accommodated in an interior of the accommodating space 101 of the insulating housing 10, two pairs of electric contact members t1, t2 which have opposite polarities, are protruded from an inner side at the bottom of the insulating housing 10, and a cap 104 covers the opening part of the insulating housing 10.
Referring to FIG. 9, this kind of switch is usually installed on a target machine horizontally. In this situation, the ball member 102 is located in the large-diameter part of the accommodating space 101 without contacting the contact members t1, t2, and the switch is at an OFF state. If the insulating housing 10 is lifted upward at an end of the cap 104 from this horizontal state, allowing the switch to tilt as shown in FIG. 10, then the ball member 102 will roll toward the left side funnel part, due to its weight. When a tilt angle of the switch exceeds 45 degrees, the ball member 102 will fall into the funnel part to contact the four contact members t1, t2, thereby constituting an ON state. Accordingly, by the movement of the ball member, and the extent of tilting of the switch, the ON/OFF operation can be carried out.
In addition, the Japanese Utility Model Patent No. 9-7475 discloses an inclination detection switch which includes an insulating substrate, a plurality of terminals inserted into terminal holes on the insulating substrate, a case-shape housing which covers this insulating substrate, and an electrically conductive ball member which is movable and contained in an interior of the housing, wherein contact parts at top ends of the terminals are formed with knife-like edges, and the ball member crosses over the knife-like edges, thereby reducing contact area of the ball member with the knife-like edges to increase contact pressure per unit area.
Furthermore, the Japanese Utility Model Patent No. 11-232973 discloses a direction detection type inclination switch, which consists of a base with a top face being in a funnel shape, at least one or more light-emitting elements arranged in a center of the funnel-like part for emitting light toward an upper part of the base, a plurality of light-receiving bodies arranged around the light-emitting element, a light shielding ball which is freely movable and mounted on the base, and a cap which accommodates this light shielding ball and covers an inner surface of the base for forming a reflection face. The inclination switch constituted in such a manner can detect the inclination direction by shielding the light receiving body in front of the moving direction, due to the free movement of the light shielding ball in the inclined direction.
However, for the switch which is disclosed by the Taiwanese Utility Model Patent No. 468865, the bottom part of its insulating housing needs to form the cone-shape funnel part at about 45 degrees, and the ON and OFF operations of the switch are dependent upon whether the tilt angle of the switch exceeds 45 degrees; that is, the tilt angle of 45 degrees is a critical angle for the operation of the switch. At this critical angle of 45 degrees, vertical component of force of the electrically conductive ball member is identical to its horizontal component of force; therefore, the ball member is under an unstable condition, and the switch is easy to manifest an intermittent and non-steady ON/OFF state. In addition, as the ball member is supported by the front ends of two pairs of contact members that are configured on a same plane, it is easy to form unstable condition that maintaining the stable operation for the switch will be difficult, if only slight tilt or vibration occurs. Moreover, as the operation angle of the switch is fixed at 45 degrees, this angle cannot be changed or adjusted.
For the detection switch disclosed by the Japanese Utility Model Patent No. 9-7475, as the contact end of the terminal is formed with the knife-like shape, the structure of terminal will become complicated. At a same time, the operation angle of the switch cannot be changed freely, either.
On the other hand, the switch disclosed by the Japanese Utility Model Patent No. 11-232973 includes the light-emitting element and a plurality of light receiving bodies, whereas the inner surface of the cap is formed with the reflection surface. Therefore, when the switch tilts, the ball member will roll to shield the light receiving body in the rolling direction, such that the light receiving body is not irradiated by the light, and is thus not operable, thereby detecting the inclination direction of the switch. This kind of switch has a complicated structure and high manufacturing cost. In a mean time, its construction is not the same as the construction and principle for turning on and off the tilt switch by directly contacting the ball member with the terminals, as disclosed by the aforementioned Taiwanese Utility Model Patent No. 468865 and the Japanese Utility Model Patent No. 9-7475.